JPH02291656A - Secondary electron multiplier and photo-electron multiplier with same secondary electron multiplier incorporated - Google Patents

Abstract

PURPOSE:To obtain a secondary electron multiplier and a photo-electron multiplier which are highly efficient by correcting the orbits of secondary electrons emitted from dynodes in the first stage, and thereby enhancing a carry-over factor over to dynodes in the second stage. CONSTITUTION:In groups 71 through 7n of dynodes, the dislocation S between the end sections 9a and 9b of an upper and a lower stage shall be set to be roughly 2/5d as usual in the second stage 72 through the (n)th stage 7n wherein d represents a dynode pitch. Only the dislocation S between the first stage 71 and the second stage 72 shall however, be set to be +1/5d<S<-1/5d by the method as described above in such a way as to be sufficiently smaller than 2/5d. This results in the characteristics of an electron carry-over factor as shown by a curve in the figure wherein the carry-over factor eta is roughly 80% representing the maximum when the dislocation S is equal to zero, eta will roughly be 60% representing the minimum when S is equal to 1/2d, similarly eta will roughly be 65% when S is equal to 2/5d, and eta will roughly be 72% when S is equal to 1/5d. This would allow an inequality of +1/5d<S<-1/5d to be maintained in order to obtain the excellent carry-over factor.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a secondary electron multiplier tube having a so-called Venetian blind dynode and a photomultiplier tube equipped with the same.

"Prior art" A photomultiplier tube using a Venetian blind dynode secondary electron multiplier has a glass tube (1) with a flat light entrance surface (2) as shown in Figure 3. A photocathode (3) is provided on the inner surface thereof, and a conductive layer (4) is applied to the inner peripheral surface. A focusing electrode (5) is placed halfway inside the glass tube (1).
) are arranged, and at the rear of this focusing electrode (5), mesh electrodes (6■)...(6n) and dynodes (71) are arranged in multiple stages.
...(7n) is provided, and the final stage dynode (
An anode (8) is provided facing the terminal (7n), and this anode (8) is connected to a lead-out terminal (not shown) to the outside. The dynodes (71)...(7n) consist of an electrode element (9) having a narrow plate shape, the long side of which extends perpendicularly to the figure, and the short side of which is the part shown in the figure. The odd-numbered stages are tilted at 45 degrees in the same direction with respect to the main axis of the multiplier tube,
The even-numbered stages are inclined at 45 degrees in the opposite direction to the odd-numbered stages.

However, in such Venetian blind type dynodes (71)...(7n), conventionally, as shown in FIG. (7n), the positional relationship of the electrode elements (9) between the upper and lower stages is
), the pitch interval is d, and the lower end (9a) of the upper electrode element (9) and the upper end (9b) of the lower electrode element (9)
Let S be the interval between . "Problem to be Solved by the Invention" As described above, when the vertical positional relationship from the first stage to the nth stage is all set to S=1d, the following problems occur. That is, normally, the voltage of the dynode is increased by 100V at each stage, such as the second stage is IOOV higher than the first stage, the third stage is 100V higher than the second stage, and so on. Here, based on Fig. 4, the third stage dynode (73
) electronic element (9)? Secondary electrons (b
), this secondary electron (b) is influenced by the electric field of the second-stage dynode (72) and the fourth-stage dynode (74), and moves to the electrode of the fourth-stage dynode (74). incident on element (9). However, only the first stage dynode (7■) is different from the second stage dynode (7■).
7. ) is located far away from the electric field of the photocathode (3).
) under the influence of the electric field of the second stage dynode (7,)
trying to enter. The secondary electrons (c) emitted from the lower half (9■) of the electrode element (9) of the first stage dynode (71) are transferred to the electrode element (9) of the second stage dynode (7■). However, the upper half (9
The secondary electron (a) emitted from 1) is the second stage (72)
An object is generated that takes a trajectory that passes through the dynode (73) and enters the upper half (9) of the electronic element (9) of the third stage dynode (73). In other words, the first stage dynode (7■)
Only the secondary electron trajectory (a) emitted from the upper half (91) of the electrode element (9) is transmitted to the electrode elements of the dynodes (7.)...(7n) of the other stages below the second stage. (9
) is emitted from the upper half (9■) of the secondary electron orbit (b
) and different? It becomes a trajectory that jumps out greatly upwards,
Electrode element (9) of the second stage dynode (7■)
8, the efficiency of incidence will deteriorate.

The present invention has two dynodes with Venetian blind type dynodes.
The purpose of this invention is to normalize the trajectory of secondary electrons in the first stage dynode in a secondary electron multiplier to obtain an efficient multiplier.

"Means for Solving the Problems" The present invention provides a secondary electron multiplier in which a plurality of dynodes are arranged in a venetian blind configuration, in which the lower end of the first stage dynode and the second stage dynode are connected to each other. The deviation from the upper end of the dynodes in the same stage is arranged so that the above-mentioned deviation for each stage is approximately - of the above-mentioned pitch. In a doubler tube, the deviation between each stage is quadratic, reaching from the pitch node of the dynode to the dynode immediately below it? The child's arrival rate is maximized. However, the arrival rate of secondary electrons from the first stage to the second stage is quite low. As a result of experiments, the arrival rate of secondary electrons is higher when there is almost no deviation between the first stage and the second stage.

"Example" An embodiment of the present invention will be described below.

In Figure 1. (7.) (7■) (7,) (7.)
are the dynode groups of the first stage, second stage, third stage, and fourth stage, respectively. There are stages up to the nth stage below, but illustration is omitted. Dynode group (71) of the present invention shown in FIG. 1...
(7n), from the second stage (72) to the nth stage (7n), as in the conventional case, the deviation S of the ends (9a) and (9b) of the upper and lower stages is approximately 1 d, where d is the dynode pitch. is set to . Disparity S between the first stage (71) and the second stage (7■)
The specific reason why only -d was made to be sufficiently smaller than -d was because the characteristics shown in FIG. 2 were obtained as a result of experiments. In other words, if the horizontal axis is the shift S, and the vertical axis is the arrival rate η of the secondary electrons that have reached the second stage (72) from the first stage (71), then when the shift S = 0, the arrival rate is η=
It showed a maximum of about 80%, and S=η=about 72%. From the above, a good arrival rate η is obtained in the shaded range in FIG.

By attaching the secondary electron multiplier constructed as described above to the electron multiplier section of a photomultiplier tube as shown in FIG. 3, an efficient photomultiplier tube can be obtained.

"Effects of the Invention" Since the present invention is configured as described above, the trajectory of the secondary electrons emitted from the first stage dynode is corrected, the rate of reaching the second stage dynode is increased, and the efficiency is increased. good 2
Secondary electron multiplier tube and photoelectron multiplier? You can get the tube.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example of dynode arrangement according to the present invention, and FIG.
The figure is a characteristic diagram of electron arrival rate, FIG. 3 is a cross-sectional view of a general photomultiplier tube, and FIG. 4 is a layout diagram of a conventional dynode. (1)...Glass tube, (2)...Light incidence surface, (3)
... Photocathode, (4) ... Conductive layer, (5) ...
・Focusing electrode, (6■) to (6n)...Mesh electrode. (
7. ) ~ (7n)... Dynode, (8)... Anode, (9)... Electrode element, (9a) (9b
)...end, (91)...upper half, (9■)...
Lower half. Applicant Hamamatsu Photonics Co., Ltd.

Claims (3)

[Claims] (1) In a secondary electron multiplier tube in which a plurality of dynodes are arranged in a Venetian blind configuration, the deviation between the lower end of the first stage dynode and the upper end of the second stage dynode is calculated as follows:
The dynodes in the same stage are arranged so that the pitch is smaller than 2/5, and the dynodes in the second and subsequent stages are arranged so that the deviation for each stage is approximately 2/5 of the pitch. Secondary electron multiplier. (2) When the deviation is S and the pitch is d, the deviation S is +2
The secondary electron multiplier according to claim 1, wherein the secondary electron multiplier is set within the range of /5d<S<-2/5d. (3) A photomultiplier tube, characterized in that the secondary electron multiplier section is equipped with the secondary electron multiplier tube according to claim (1) or (2).